Abstract:
Fission product yields (FPY) have long been recognized as one of the most distinctive characteristics of the fission process, showing a strong correlation with excitation energy and the fissioning species. The energy dependence of FPY is essential data for the advancement of nuclear energy and the enhancement of nuclear technology applications. As such, it has become a focal point in both experimental and theoretical research on FPY. Given the intrinsic complexity of the fission mechanism, conducting consistent and systematic studies on the dependence of FPY on incident neutron energy remains a challenging task. To address this, advanced nuclear models of the fission process are being developed, alongside experimental measurements of both integral and differential energy-dependent FPY. A significant gap in current research lies in the validation of energy-dependent FPY data for the three major actinides of
235U,
238U, and
239Pu across a wide energy range. This lack of comprehensive study provides the primary motivation for this work. A novel approach was introduced to validate the energy dependence of FPY based on a well-defined neutron-energy spectrum and the cross section of fission nuclei. The effectiveness of this method was demonstrated by validating energy-dependent FPY data using the neutron spectrum from
252Cf spontaneous fission and the neutron-induced
235U fission cross section as a case study. The primary focus is on three key fission products,
95Zr,
99Mo, and
147Nd, which are critical nuclides in the fission process. The equivalent yields within the fission spectrum’s neutron energy range were then calculated, and these calculations were compared to the integral yields measured in the
252Cf spontaneous fission neutron spectrum. The results indicate that comparing the fission spectrum neutron equivalent yields with integral measurement yields is a reliable method for assessing the validity of yield-energy dependent FPY data, particularly in the fission spectrum neutron energy range. The trend in the yield-energy dependence between the thermal energy point and 4 MeV has a significant impact on the calculated equivalent yields of fission spectrum neutrons, due to the fact that fission spectrum neutrons exhibit the highest neutron flux in this energy range. These findings emphasize the importance of understanding the yield-energy dependence within a certain energy range and illustrate the method’s potential for improving the reliability of FPY models. An idea to indirectly verify the validity of the yield-energy dependence by carrying out integral fission product yield experiments was proposed, offering valuable insights for future research in this area.